2TLA020052R1000 24 V dc Safety Relay – With 2 Safety Contacts Compatible With Light Beam/Curtain. The Vital safety device from ABB is the heart of a new solution which makes it possible to install/connect many different types of safety device in the same safety circuit and still achieve safety category 4 in accordance with EN 954-1/EN ISO 13849-1. The Vital module is based upon a dynamic single-channel concept as opposed to conventional dual-channel safety relays.